Grounding issue - Nait 5si & Trichord Dino Mk3

Hi all,

Looking for some guidance please. I seem to be having a grounding issue with a Trichord Dino Mk3 connected to any of the inputs on my Naim 5si. There is a slight hum in the background (other than the Nait’s transformer) that increases as I turn the volume up on the Nait. It’s very quiet, but there, when the volume knob is at the 9–10 o’clock position, my usual listening level. I can’t actually hear it when music is playing. I think most would say, “Why bother if you can’t hear it when playing music?” However, it is bugging me as I never experienced this hum with my Brio and this Dino Mk3 in the past.

I’ve carried out this troubleshooting with no other sources connected, simply the phono stage and its PSU. Dino without power going to it and connected to Nait = zero hum. As soon as I turn on the power supply = hum. Adding other sources back into the mix does not increase nor decrease the hum. So I’m fairly certain it’s the phono stage that’s the culprit.

I’ve also tried: all of the inputs; different RCA–RCA interconnects; RCA–DIN interconnects from Naim and Chord; switching power leads to a Russ Andrews YellO or a Black Rhodium Libra; plugging the Dino Mk3 and Nait directly into the same wall socket; and, ensuring the Nait, Dino Mk3 and Planar 3 are all plugged into the same 6-gang extension lead. The hum remains.

I emailed Trichord and they came back with:

The casework of the Dino+ power supply is directly connected to Earth for safety purposes, but this earth connection does not carry through to the Dino itself. This means that the Dino is ‘floating’ from earth, giving you the opportunity of grounding in a way that should overcome any hum problems.

Another possibility is that there is some kind of grounding issue with your turntable or tonearm. Again this can vary between different set-ups. This is detectable by touching the tonearm and getting an increase in hum.

Have you tried connecting a wire directly from the ground terminal on the Dino directly to mains earth. You can attach this wire to the earth pin in a mains plug to try this out. Just be sure that it IS the earth pin.

Touching the tonearm didn’t make any different. I tried connecting a wire from the Dino’s ground terminal to mains earth as per a post in this thread:

That didn’t help either. Do I need to connect a wire to the Dino Mk3 ground terminal and the Nait chassis somehow? If so, how? Troubleshooting guidance and thoughts on potential solutions would be much appreciated!

What is the turntable?

Rega P3 (2016)

IIRC Rega earth through the screen of one of the RCAs. Trouble is it can sometimes be problematic, especially if there’s a poor contact somewhere, particularly between the RCAs and the phono sockets on the phono stage. There’s plenty online about how to better earth a Rega deck, however, just as a test, try swapping the arm plugs around the phono stage to see whether it makes any difference (sometimes it does).

Where is the Dino head unit located - is it away from its own PSU and others ?

Thanks Richard. I believe you are correct about Rega grounding. Googling around, I found, “Rega grounds the tone arm tube to the phono preamp using the shield of the left channel of the phono interconnect cable.”

If I’m understanding your suggestion correctly, I should swap the left (black) and right (red) RCA ends from the TT phono cable going into the Dino? Have done that - did not make a difference :frowning:

I’ve seen a few suggestions out there on alternative ways to earth a Rega deck - will try later tonight.

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Yes. Different shelves on the rack. Have tried moving further (and closer) away from the PSU - no affect on the hum.

Ok. Just one additional thing - when you disconnected all the sources apart from the Dino and Rega, did you also disconnect the REL sub ? If not, try it again with the sub disconnected.

Ah. Good point. I did not! Will try that. Although I’m not using the stock Rel high-level cable, but the Naim-specific one from Design-A-Cable. Still, I should honour the troubleshooting process.

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My previous Trichord Dino Mk3 (and PSU) sometimes had a similar issue. The issue was the connection between the RCA cable and the Trichord Dino and could be fixed by firmly pushing the RCA cable plug and making sure it was fully inserted into the Dino.

ORLY? OK, thanks, I’ll take a look and see if that makes any difference. Mind you, I’ve unplugged and re-plugged the phono leads from the turntable that many times now … :persevere:

We have the Dino / PS / Rega P3 combination into a 282 and have never experienced hum. We now have the PS a good distance from the phono amp but even when they were alongside each other we didn’t have hum.

I know this doesn’t help, but if we have prevented it in some way, I would guess it was by using good Chord phono leads from the phono to the 282. Possibly the earthing being determined by our Naim streamer helps too?

Is the hum a new ‘feature’? I’d be questioning the 5si next.
Hope you get it solved.

Just had time to check this over lunch. The REL sub and all other sources were disconnected AND just the Dino & RP3 connected. No joy, the hum remains :frowning:

Double (and triple) checked. Phono leads are inserted into the Dino as far as is possible.

Back to the drawing board.

Ok - ruled that out. With sub still disconnected and if you only have the Dino and 5si connected. (Disconnect Rega from Dino) do you get hum ?

It’s been there since I swapped out my Rega Brio for the Nait 5si, which was March/April this year. The Brio and the Dino + PSU were deadly quiet (so quiet it was impressive!).

I’ve just not had the time (nor inclination) to tackle this with a few other things taking precedence. Currently using Chord Chrysalis RCA-DIN to connect Dino to Nait 5si. Have also tried Naim RCA-DIN and Chord Clearway RCA-DIN.

Yep. Although without the RP3 connected, there is now also something like a background hiss.
And if I touch the Dino case, the hum becomes more prominent/louder.

Thanks for your help with the troubleshooting btw @james_n !

Out of interest, which version of Brio did you have before you changed to the Nait ?

with a rega 3 and nait xs or sn2 i had hum especially as the arm went towards the centre
in the background and ‘under the music’
at the dealers who checked it no hum with a rega brio
took it home and still humming there with either amp
tried earth lead to a seperate mains plug from phono pre and also the amp no change
tried mu metal sheets etc etc
gave up in the end and got a tt with a specific grounding terminal and no hum at all
lots online about this and members here didn’t seem to have the same problem.whilst i loved the rega it was easier to change the tt and move on
good luck and i hope you find a solution!

Sorry to hear that. The Dino is really an impressively quiet phono stage otherwise. I hope you get to the bottom of the problem soon.

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